Fiberboard



May-11, 1937. J. N. DEVEREUX FIBERBOARD Original Filed Jan. 23, 1933Patented- May 11, 1937 UNITED STATES PATENT OFFICE Deverenx,

ratrix of James N. Devereux, deceased, assignor to United States GypsumQompany, Chicago, 111., a corporation of Illinois Original applicationJanuary 23, 1933, Serial No.

4,1933, Serial No. 683,659

Claims.

My present inventionrelatesgenerally to fiber board or fiber sheets ofthe type commonly used inthe construction of buildings, in wal1s,'roofs,ceilings, partitions, and the like, and more par- 5 ticularly to fiberboard asmanufactured according to the method, and by means of theapparatus, described and claimed in my Patent Number 1,997,136, grantedApril 9, 1935, of which the prosent application is a division.

wood, comstalk or other suitable fibers, in a single ply, has been roughand unsightly in appearance, and unsuitable for the direct applicationof paints, wall paper and other decorative materials.

as commonly used onbuilding interiors. Some effort has been made tocombine two webs or plies, one of which is smooth and water resistant,but such plies have been in the nature of separate layers which aretoo'readily torn apart and this is highly objectionable.

It is the primary object'of my invention, therefore, to provide fiberboard having a body and at least one surface constituting, in effect,two plies, although not separable, one from the other, and

of which the surface ply is smooth and water resistant so that itmay bewashed when soiled, and is well adapted to receive plastic paints, wallpaper, and the like applied directly thereto, with pleasing appearance.

A still further object is the provision of a multiply fiber board, oneply of which is in the nature of a non-separable skin on the body of theboard,

36 content substantially greaterthan that of the A still further objectof my invention is to provide fiber board having a body and at leastoneskin surface of a tough, water resistant character. 40 the body and saidsurfacebeing formed of the same materials, of which the fine fibers anda preponderance of the chemical constituents are concentrated in thesaid skin surface. a With the above, and certain other objects andadvantages in mind, my invention resides in the fiber board to be nowdescribed with reference to the accompanying drawing, which forms a partv of this specification, and in which,

Figure 1 is a perspective view of a section of fiber board constructedaccording to my inven tion.

Figure 2 isa transverse sectional view through a section 56 and,

Up to the present time. fiber board formed of thereof, showing a singlesurface skin,

Divided and this application August Figure 3 is a similar view showing asurface skin on both top and bottom of the body.

Referring nowto these figures, I have shown in Figures 1 and 2, fiberboard, the body i5 of which has upon one side thereof, a skin coat orsurface ply i6, which is formed of the same material as the body i5,though containing only short, fine fibers and a preponderance of thechemical constituents of the material, so as to present a tough, waterresistant finish which,will be sufilciently smooth to present a goodappearance when papered or painted and which will be integral with thebody to such an extent as to prevent tearing thereof from the body.

Entering into the formation of the board, which as to themethod of, andapparatus for, making the same, is fully described and claimed in myabove mentioned 'Patent No. 1,997,136, only so far as it concerns theultimate structure thereof, a watery mixture of coerse and fine fibersof the material employed-is agitated and aerated. with an admixture ofsizing materials, such as I alum and rosin. The reaction between thealum and the rosin size, of course,produces a precipitate of aluminumresinate, commonly termed precipitated size, The result of suchagitation and aeration is to float to the surface of the mixture thefine fibers and the products of the reaction between the sizingmaterials and the natural hardness or chemicals of the water. As theboard is formed, this foam is killed in such manner as to deposit thefoam-carried or flotation products just mentioned on the surfacethereof. forming the tough, smooth skin It, in which is thusconcentratedthe fine fibers and reaction products, so that a muchgreater density is found in the skin surface and it has a,,much higherash content than the lighter, more porous body i5 which has but littleof the reaction products and all of the long fibers.

Thus it is obvious that the skin surface l6 so formed is not a separateply in the ordinary sense, but is an inseparable, integral skin whichadds to the tensile strength of the board as a whole, and admits ofready. cleaning and decoration, and provides anideal board for insulatinand sound absorbing purposes due to its extremely light weight.

As an example of its advantages, my improved board presents in its skinsurface "an ash content approximately five times the ash content of thecenter of the body I! and approximately twice the ash content of theback surfaceof the body. The following table gives the analysis as toash content of my improved sized and unsized board,

in percentages, as compared with present boards A and B of othermanufactures,

My board IA, IBY Sized Unsised 6. 35 3. 02 1. 45 2. B35 1. 34 0. 834 O.474 2. 34 3. 03 1. 655 1. B1 2. 01

The above indicated ash content of theslrin surface, center and backsurface of my improved board has been found to very materially add toits desirable water proof qualities.

As to the skin surface of my improved board, I have found that it hasthe following composi tion: fiber 91.76 percent; rosin 3.34 percent,-andinorganic matter 4.90 percent.

In some cases it may be desirable to provide the board'with a skinsurface I? on its side opposite to the skin surface it as l. have shownin Figure 3, and it is to be understood the foregoing descriptionrelative to the skin surface it applies equally to the opposite surfaceii.

Having'thus fully described my invention, what I claim is,

l. A fiber board comprising a body mass of relatively coarse celluloslcfibers and a thin shinlike surface portion of finer fibers of the samemind of cellulose, said surface portion also containing adhered to andinterspersed with said fibers an amount of precipitated size greatlyerr-- ceeding' that adhered to the coarser fibers in the 45 body of theboard. 4

2. A fiber board comprising a body mass of relatively coarse cellulosicfibers and a thin skinlilse surface portion of finer fibers of the samekind of cellulose, said surface portion also containing adhered to andinterspersed with said fibers an amount of precipitated size greatlyexceeding that adhered to the coarser fibers in the body of the board,said surface portionhaving been deposited during the formation of theboard "from foam carrying in suspension fine cellulosic wood pulpfibers, said surface portion also con- 3 taining adlgeredto andinterspersed with said fibers an amount of precipitated aluminumresinate greati v exceeding that adhered to the coarse fibers in thebody of the board, whereby said surface is rendered water-resistant andadapted to receive a decorative coating.

. 5. A. fiber board comprising s. body mass of relatively coarsemechanical wood pulp fibers and a thin nonseparable skin of fibers onthe body of the board, said skin having a tough, close-grained, smoothand water-resistant surface and containing adhered to and interspersedwith the fibers thereof precipitated rosin compounds of alum and thehardness-imparting constituents of water, said skin being formed by thedestruction of a foam carrying fine fibers and said precipitate, theamount of precipitated material on the fine fibers greatlyexceeding-that which adheres to the coarse fibers in the body of theboard, whereby said surface is rendered water-resistant and adapted toreceive a decorative coating.

